Photosensitive material and image forming method

ABSTRACT

A photosensitive material comprises a photosensitive and heat-developable element and a photopolymerizable element which are contained in the same layer. The photopolymerizable element comprises at least a polymerizable polymer precursor having a melting point of 35° C. or more. The photosensitive material is exposed to light with at least one wavelength within the wavelength region of from 400 nm to 900 nm, heated at 60° to 180° C., and exposed to light with at least one wavelength within the wavelength region of from 250 to 700 nm, and thus an unexposed area in the photosensitive layer which is an area not exposed to light with at least one wavelength within the wavelength region of from 400 nm to 900 nm is polymerized.

This application is a division of application Ser. No. 07/477,124 filedFeb. 7, 1990, U.S. Pat. No. 5,064,744, which, in turn, is a continuationof application Ser. No. 07/314,141, filed Feb. 23, 1989, now abandoned.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a photosensitive material that forms apolymer image by heating or exposure to light, and an image formingmethod which employs the photosensitive material.

2. Related Background Art

Energies used to form or record an image include light, sound,electricity, magnetism, heat, radiations such as electron rays andX-rays, and chemical energy, among which, in particular, widely used arelight, electricity, heat energy, or a combination of any of these.

For example, the image forming method that employs the combination oflight energy with chemical energy includes a silver salt photographicprocess and a method in which a diazo copying paper is used. The methodthat employs the combination of light energy with electric energyincludes an electrophotographic system. Also, the method that utilizesheat energy includes a method in which a thermal recording paper ortransfer recording paper is used. On the other hand, known as the methodthat utilizes electric energy is a method in which an electrostaticrecording paper, electrothermal recording paper, or electrosensitiverecording paper is used.

Of the above image forming methods, the silver salt photographic processcan obtain an image having a high resolution. The silver saltphotographic process, however, requires the developing and fixing thatuses complicated liquid compositions, and the drying of an image (or aprint).

Now, development is energetically made on image forming methods that canform an image through a simple processing.

For example, U.S. Pat. No. 4,629,676 teaches a method in whichpolymerization reaction under dry (thermal) conditions is caused by thephotosensitive reaction of silver halide that acts as a trigger, to forman image comprising a polymer.

This method has the advantage that any complicated wet processing is notrequired, but has had the disadvantage that the polymer formation rate(i.e., polymerization rate of a polymeric compound) is so low that ittakes a long time to form the polymer image. Incidentally, thisdisadvantage arises presumably because of a reaction intermediate (whichfunctions as a polymerization initiator) formed, in the course ofheating, by the reaction between silver produced from silver halide byimagewise exposure and a reducing agent, which intermediate isconsidered to be so stable and has so low activity as the polymerizationinitiator that the polymerization reaction can not proceed so rapidly.

On the other hand, to cope with this problem to accelerate thepolymerization, Japanese Unexamined Patent Publication No. 62-70836discloses a method in which a thermal polymerization initiator is used.

This method comprises forming a latent image comprising silver metalproduced from silver halide by imagewise exposure, converting, byutilizing a catalytic action of the above silver metal and underheating, a reducing agent into an oxidized product having apolymerization inhibitory power different from that of said reducingagent, thereby producing a difference in the polymerization inhibitorypower between the reducing agent and the resulting oxidized product andalso causing a thermal polymerization reaction utilizing the thermalpolymerization initiator, thus forming a polymer image in accordancewith the difference in the polymerization inhibitory power.

This method, however, has been accompanied with the disadvantage that agood contrast can be made with difficulty in the polymer image.

This disadvantage arises presumably because the oxidation-reductionreaction taking place in a latent image portion to form the oxidizedproduct and the polymerization reaction to form the polymer image areallowed to take place in the same heating step, so that these reactionsmay proceed in a competitive fashion and thus the respective reactionsmay not proceed in a good efficiency.

Also, the image formation according to this method is very unstable inthat, for example, the areas on which the polymer is formed may turninto exposed areas or unexposed areas even because of a slight change inthe amount of the reducing agent.

In addition, U.S. Pat. No. 4,649,098 discloses a method in which areducing agent having a polymerization inhibitory power is brought intoan oxidized product by imagewise consumption thereof, that is, imagewiseoxidation (at imagewise exposed areas) in the course of the developingof silver halide, and, after imagewise inhibition (at imagewiseunexposed areas) of polymerization reaction by the action of theresidual reducing agent, light energy is uniformly applied onto thewhole area from outside to cause photopolymerization at the part wherethe reducing agent has been consumed, thus forming a polymer image.

The above method has the advantages that it can achieve a highsensitivity in the writing of a latent image since the silver halide isutilized, and the steps of form the writing for the formation of animage up to the whole areal exposure can be separated in a goodefficiency. It, however, is difficult to obtain a polymer image having asufficient contrast. This is caused for the following reason.

The reducing agent used in the above method is in itself a reducingagent that acts as a polymerization inhibitor and ceases to act as thepolymerization inhibitor after the reduction of silver halide. Hence thereducing agent at the imagewise exposed area must be sufficientlyconverted into the oxidized product, in order that the polymerizationmay be sufficiently achieved. However, the application of heat energy ina sufficient amount upon carrying out the development, with theintention to sufficiently convert the reducing agent at the imagewiseexposed area into the oxidized product, may cause an unauthorizedoxidation-reduction reaction at the imagewise unexposed areas. On theother hand, the application of heat energy upon a reduced amount incarrying out the development, with the intention to prevent theoxidation-reduction reaction from taking place at the imagewiseunexposed area, may conversely make the oxidation-reduction reaction notto sufficiently proceed at the exposed areas. Since in this instance theimagewise exposed area of an oxidation-reduction image is polymerizedwith difficulty, the light energy in carrying out the whole arealexposure must be applied in an increased amount. This may cause anunauthorized polymerization at the unexposed areas with increase in theamount thereof, eventually making it impossible to obtain the polymerimage with a sufficient contrast.

The polymer image to be formed according to the methods as describedabove is an image comprising a polymerized area and an unpolymerizedarea. Aiming at making this polymer image visible and further forming itinto a color image, U.S. Pat. No. 4,649,098 and so forth disclosevarious methods that utilize the difference in physical properties andso forth between the polymerized area and unpolymerized area. Forexample, proposed are a method in which a treatment is made using aliquid that does not dissolve the polymerized area and dissolves thelayer of the unpolymerized area, to dissolve out and remove theunpolymerized area (i.e., etching); a method in which, utilizing adifference in adhesion between the polymerized area and unpolymerizedarea, a sheet such as a plastic film is adhered and thereafter peeled toseparate the polymerized area from unpolymerized area under dryconditions (i.e., peeling-apart); in the case that the polymer image isformed into a color image, a method in which a photopolymerizable layeris previously colored with use of a pigment or dye, which is thensubjected to dissolving-out (i.e., the above etching) or peeling (i.e.,the above peeling-apart) to form the color image, or a method in which,utilizing the adhesion at the unpolymerized area, a coloring powder isapplied to make selective coloring (i.e., toning or inking), or,utilizing a difference in liquid-permeability between the polymerizedarea and unpolymerized area, the unpolymerized area is selectively dyedby treating it with a dye solution.

However, no polymer image having a sufficient contrast can be obtainedin the conventional polymer image forming methods as discussed above,and hence, even with employment of any of the above methods for makingthe image visible or forming it into a color image, the visible imageand color image which are obtained from such a polymer image can nothave any sufficient contrast, and particularly it has been difficult toobtain highly detailed visible image and color image.

To cope with the above, the present inventors have even proposed aphotosensitive composition, a photosensitive material, and an imageforming method, in which an oxidized product having a polymerizationinhibitory power is formed by exposure to light and heating, andthereafter a polymer image is formed at an imagewise unexposed area(U.S. Patent Application filed Jan. 29, 1989, based on Japanese PatentApplication Nos. 63-17155, 63-18502, 63-183441, 63-251958 and 1-1153)

SUMMARY OF THE INVENTION

An object of the present invention is to provide a photosensitivecomposition and a photosensitive material that form a polymer image atthe above imagewise unexposed area, and a photosensitive composition anda photosensitive material that have a good green storage stability andalso can form an image with a high resolution.

Here, "green storage" indicates that the photosensitive composition ormaterial is stored as it is, until it is subjected to image-exposure.

Another object of the present invention is to provide an image formingmethod, comprising forming a polymer image on a photosensitive materialin which a photosensitive composition having achieved the above subjectmay have been dispersed in a microcapsular state, and thereaftertransferring an unpolymerized area to an image receiving paper to form acolor image (hereinafter described as "the capsule method"), which is animage forming method that can obtain an image with a good resolution.

The present invention that can achieve the above objects provides aphotosensitive composition containing at least one of a photosensitivesilver salt, a reducing agent and a polymerizable polymer precursor,wherein the polymerizable polymer precursor comprises at least onehaving a melting point of 35° C. or more, and said reducing agentcomprises at least one of the compounds represented by Formula (I), (II)and (III), described later; and the photosensitive material comprisingthe photosensitive composition which may be contained therein in amicrocapsular state.

The present invention also provides an image forming method, comprisingsubjecting the above photosensitive material to imagewise exposure toform a latent image originating from the photosensitive silver saltand/or reducing agent, and thereafter, utilizing said latent image,causing polymerization to proceed at an imagewise unexposed area to forma polymer image, and also an image forming method, comprisingtransferring a substantially unpolymerized area to an image receivingmedium by heating and pressing.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A, 1B and 1C and FIGS. 2A, 2B and 2C are diagramatical crosssections to illustrate respective steps in the image forming method ofthe present invention;

FIGS. 3 and 4 are diagramatical cross sections to illustrate therespective steps of making an image visible, in the method of thepresent invention;

FIGS. 5A to 5D are diagramatical cross sections of the photosensitivematerial of the present invention; and

FIG. 5E is a diagrammatical cross section to illustrate an embodiment ofa photosensitive layer 1 in the photosensitive material of the presentinvention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The photosensitive composition and photosensitive material of thepresent invention contain a polymerizable polymer precursor having amelting point of 35° C. or more, and at least one of the compoundsrepresented by Formulas (I), (II) and (III). ##STR1##

In the above Formulas (I), (II) and (III), R¹, R², R³, R⁵ and R⁶ eachindependently represent a hydrogen atom, a halogen atom, a hydroxylgroup, a substituted or unsubstituted alkyl group, a substituted orunsubstituted aralkyl group, a substituted or unsubstituted aryl group,an alkoxyl group, or a substituted or unsubstituted cycloalkyl group; R⁴represents a hydrogen atom, a halogen atom, a substituted orunsubstituted alkyl group, a substituted or unsubstituted aralkyl group,a substituted or unsubstituted aryl group, a substituted orunsubstituted cycloalkyl group, a carboxyl group, or a carboxylic acidester group; A represents an oxygen atom, or a sulfur atom; R representsa hydrogen atom, an unsubstituted alkyl group, or a substituted orunsubstituted aralkyl group; n represents 0 or 1; and Z is a divalentlinking group and represents an alkylidene group, an aralkylidene group,or a sulfur atom.

Using a photosensitive material having a photosensitive layer made ofthis photosensitive composition, a good image which is free of imageunclearness is formed by carrying out the method disclosed in JapaneseUnexamined Patent Publications No. 62-78552 and No. 62-81635, i.e. themethod in which a polymerizable polymer is formed using a silver salt,and in which, for the purpose of obtaining an end color image, an imageoriginating from a difference in breaking strength of capsules betweenthe polymerizable polymer formed area and unformed area is transferredto an image receiving medium by heating and pressing.

However, the photosensitive composition of the present invention can benot only applied in the method disclosed in the Japanese UnexaminedPatent Publications No. 62-78552 and No. 62-81635 but also applied in amethod of forming a color image or a polymer image by the etching,peeling-apart, or toning and inking after polymerization treatment,where it is possible to obtain an image with a good green storagestability and an excellent resolution.

More specifically, the photosensitive composition of the presentinvention enables suppression of the dark reaction during the greenstorage, has eliminated the problems of blocking since thephotosensitive layer has been improved to become non-sticky, and alsoenables suppression of a strain produced in the photosensitive layerupon carrying out the heat treatment, so that the polymer image andcolor image with a high resolution can be obtained.

Other advantages of the present invention will be described for eachimage forming method. In instances in which the capsule method is used,it is possible to suppress an image from spreading when theunpolymerized area is transferred to the image receiving medium, andsimultaneously to obviate the problem of unpleasant odor that may occurwhen a polymerizable polymer precursor having a melting point of lessthan 35° C. has been usually used. It is also possible to improve thestorage stability of the image once having been transferred to the imagereceiving medium. More specifically, it becomes possible to eliminatethe discoloration problem that a color image is reversely reacted with aleuco dye, which may occur when the polymerizable polymer precursorsdescribed in the Japanese Unexamined Patent Publications No. 62-78552and No. 62-81635 are used, or lessen the image unclearness that may becaused by the spreading of the polymerizable polymer precursor in theimage receiving medium during the storage of images. In instances inwhich the inking and toning were applied, the advantage of ease inhandling is brought about because the polymer image formed is notsticky.

In instances in which the peeling-apart is applied, it becomes possibleto stably obtain a peeled image since the cohesive failure, which usedto occur in the photosensitive layer because of differences in operationenvironments, has been decreased.

As described above, the present invention was found to have variousadvantages in addition to the improvement in green storage stability andimprovement in resolution.

In the present invention, the "melting point" refers to the temperatureat which a substance in a crystalline or solid state is melted orsoftened, or the temperature at which a substance in a waxy state ismelted to turn into a transparent state.

The reason why the storage stability is improved by using thepolymerizable polymer precursor having a melting point of 35° C. or moreis not clear, but presumably because of the following:

1. Because of less moisture absorption, the dark reaction between thesilver salt and the reducing agent of the present invention proceedswith difficulty.

2. The hydrogen bond between the urethane group or ester group of thepolymerizable polymer precursor and the hydroxyl group of the reducingagent results in the existence of the reducing agent in a stable state,and hence the dark reaction proceeds with difficulty.

Also the reason why the resolution is improved is presumably that thestrain of the photosensitive layer is lessened in carrying out theheating, and, in addition thereto, probably that employment of thepolymerizable polymer precursor having a melting point of 35° C. or moreinfluences the oxidation-reduction reaction between the silver salt andthe reducing agent of the present invention.

The present invention may have been achieved by the facts other than theabove, but it is not an objective of the present application toinvestigate the reasons.

The means of polymerization in the present invention should rely on amethod in which a polymer image is formed in the imagewise unexposedarea by either thermopolymerization or photopolymerization, andpreferably by photopolymerization in view of the goodness in contrast.

In a preferred embodiment, the photosensitive material contains a silverhalide and a photopolymerization initiator. In such an embodiment, thephotosensitive material is subjected to imagewise exposure under anenergy of up to 1 mJ/cm² at maximum, through a mask having an opticaldensity of 3.0 or more at the masked portion, and using the light havinga wavelength to which the silver halide has a sensitivity, asexemplified by light of 400 nm or less in the case that the silverhalide comprises silver chloride and has not been sensitized, light of450 nm or less in the case that the silver halide comprises silverbromide and has not been sensitized, light of 480 nm or less in the casethat the silver halide comprises silver iodobromide and has not beensensitized, and light within the sensitizing region in the case that thesilver halide has been sensitized (e.g., light of about 900 nm or lesswhen it has been infrared-sensitized); and then subjected to heating attemperatures of from 60° C. to 180° C., and preferably from 100° C. to150° C., for a time of from 1 second to 5 minutes, and preferably from 3seconds to 60 seconds, by use of a hot plate, a heat roller or the like.At this stage, an optical image may be formed or may not be formed onthe imagewise exposed area. Thereafter, the whole areal exposure isapplied under an energy of 500 J/cm² at maximum and using the lighthaving a wavelength to which the photopolymerization initiator has asensitivity in the instance of the photopolymerization, e.g., light offrom 250 nm to 700 nm, and more preferably from 300 nm to 500 nm,whereupon the imagewise unexposed area is polymerized.

In the instance of the thermopolymerization, such heating is carried outat 70° to 180° C., and preferably 80° to 150° C., for 1 to 100 seconds.The heating treatment described above may be substituted for thisheating, or this heating may be carried out afresh.

The photosensitive composition of the present invention will bedescribed below in greater detail.

The polymerizable polymer precursor contained in this photosensitivecomposition may preferably be a bifunctional greater compound in view ofthe sensitivity, and one or two or more kinds thereof can be used.

In the instance where the capsule method is used, the polymerizablepolymer precursor is required to be a compound that may bring theunpolymerized area into substantial melting, or show a tackiness enoughfor that area to be transferred, in accordance with the state of heatingin carrying out the transfer.

Polymerizable polymer precursors comprised of a polymer having apolymerizable functional chain on its side chain are not preferred sincethe precursors, many of which are solid at room temperature, do not melteven under a heated state, or difficult to contrast with theunpolymerized area even if the polymerization takes place.

In particular, in the instances of the etching, inking, toning, andpeeling-apart, the polymerizable polymer precursors comprised of apolymer having a polymerizable functional chain on its terminal are notpreferred since differences in the solvent solubility, adhesion andstickiness between the polymerized and unpolymerized areas causedifficulties.

Also in the instance where the capsule method is utilized, thepolymerizable polymer precursor may preferably have a melting point of140° C. or less for the reason that the transfer must be achievable onthe image receiving medium at temperatures lower than theoxidation-reduction reaction temperature.

Polymerizable polymer precursors of an acrylamide type as exemplified byacrylamide, methylenebisacrylamide and ethylenebisacrylamide are alsounsuitable to a method in which they are incorporated, in a capsularstate or oil-droplet state into an image forming layer. This is becausethey are soluble in water.

The polymerizable polymer precursor used in the present inventionincludes bifunctional or more polyester acrylate or polyurethaneacrylate, and also include ester condensates of hexamethylene glycol,octamethylene glycol, decamethylene glycol, dodecamethylene glycol ortrimethylol propane with acryloxyacetic acid or acryloxypropionic acid,and reaction products of cyclohexylenediisocyanate,4,4'-methylenebis(cyclohexylisocyanate),1,4-cyclohexylenemethylenediisocyanate or phenylenediisocyanate withhydroxyalkylacrylate or hydroxyalkoxyalkylacrylate. Specific examplesthereof are set out below, but said polymer precursors are by no meanslimited to these.

Bis{4-[2-acryloxy)ethoxycarbamoyl]cyclohexyl}methane (m.p. 126°-129°C.), bis{4-[2-acryloxy)ethoxycarbamoyl]phenyl}methane (m.p. 75°-78° C.),1,6-bis[2-(acryloxy)acetoxy]hexane (m.p. 63°-65° C.),1,12-bis[2-(acryloxy)acetoxy]dodecane (m.p. 70°-72° C.),1,4-bis[2-(acryloxyacetoxy)ethoxycarbamolymethyl]cyclohexane (m.p.104°-106° C.), 1,3-bis[2-(acryloxyacetoxy)ethoxycarbamoylmethyl]benzene(m.p. 67°-70° C.),bis{4-[2-(acryloxyacetoxy)isopropoxycarbamoyl]phenyl}methane (m.p.71°-74° C.), 2,4-bis[2-(acryloxy)ethoxycarbamoyl]toluene (m.p. 75°-77°C.), 2,4-bis[2-(acryloxyacetoxy) ethoxycarbamoyl]toluene (m.p. 72°-74°C.), 1,6-bis[2-(acryloxyacetoxy)ethoxycarbamoyl]hexane (m.p. 125°-127°C.), and bis{4-[3-(acryloxy)propoxycarbamoyl]cyclohexyl}methane (m.p.51°-55° C.).

It is also possible to use a polymerizable polymer precursor having amelting point of less than 35° C. in combination with the abovecompounds, so long as the present invention does not deviate from whatis the objective.

Such polymerizable polymer precursor may include monovalent monomers asexemplified by styrene, methylstyrene, chlorostyrene, bromostyrene,methoxystyrene, dimethylaminostyrene, cyanostyrene, aminostyrene,acrylic acid, methyl acrylate, ethyl acrylate, cyclohexyl acrylate,methacrylic acid, methyl methacrylate, ethyl methacrylate, propylmethacrylate, butyl methacrylate, phenyl methacrylate, cyclohexylmethacrylate, N-vinylimidazole, N-methyl-2-vinylimidazole, propyl vinylether, butyl vinyl ether, isobutyl vinyl ether, β-chloroethyl vinylether, phenyl vinyl ether, p-methylphenyl vinyl ether and p-chlorophenylvinyl ether; divalent monomers as exemplified by divinylbenzene, oxalicacid di(ethyl acrylate), oxalic acid di(methyl ethyl acrylate), malonicacid di(ethyl acrylate), malonic acid di(methyl ethyl acrylate),succinic acid di(ethyl acrylate), glutaric acid di(ethyl acrylate),adipic acid di(ethyl acrylate), maleic acid di(ethyl acrylate), fumaricacid di(ethyl acrylate), β,β'-dimethylglutaric acid di(ethyl acrylate),oxalic acid di(ethyl methacrylate), oxalic acid di(methyl ethylmethacrylate), malonic acid di(ethyl methacrylate), malonic aciddi(methyl ethyl methacrylate), succinic acid di(ethyl methacrylate),succinic acid di(methyl ethyl methacrylate), glutaric acid di(ethylmethacrylate), adipic acid di(ethyl methacrylate), maleic acid di(ethylmethacrylate), fumaric acid di(methyl ethyl methacrylate), andβ,β'-dimethylglutaric acid di(ethyl methacrylate); trivalent monomers asexemplified by pentaerythritol triacrylate, pentaerythritoltrimethacrylate, pentaerythritol tri(hydroxystyrene), cyanuric acidtriacrylate, cyanuric acid trimethacrylate, 1,1,1-trimethylolpropanetriacrylate, 1,1,1-trimethylolpropane trimethacrylate,1,1,1-trimethylolpropane tri(ethyl acrylate), and cyanuric acidtri(ethyl vinyl ether); tetravalent monomers as exemplified bytetra(acryloxymethyl)methane, and tetra(methacryloxymethyl)methane;hexavalent monomers as exemplified by dipentaerithritol hexaacrylate,dipentaerithritol hexamethacrylate; and also a polymerizable polymerprecursor comprising a reactive vinyl group remaining at the terminal ofan oligomer or polymer, or a polymerizable polymer precursor comprisinga reactive vinyl group remaining at the side chain of an oligomer orpolymer.

In the instance where the polymerizable polymer precursor is used in acapsular state, a method in which the compound is encapsulated byheating and melting and a method in which it is encapsulated bydissolving it in a solvent may be employed. Provided that, when thelatter case is employed, it is necessary to use a method in which nosolvent may remain in the capsule, and, for example, the methoddisclosed in Japanese Unexamined Patent Publication No. 63-80838, ispreferred. Capsule films that can be used include known films ofgelatin, polyurethane, polyurea, urea-formalin, melamine-formalin, etc.

As specific encapsulation methods, the encapsulation methods hithertoused in carbonless paper can be utilized, and they include, for example,the methods described in U.S. Pat. Nos. 2,730,456 and 2,800,457,Japanese Patent Publication Nos. 36-9168, 37-12379, 37-7730 and No.43-23909.

In the instances where not the capsule method but the etching,peeling-apart, and inking and toning are carried out, it is requiredthat the photosensitive silver salt, reducing agent, polymerizationinitiator and polymerizable polymer precursor to be contained in thesame layer.

The layer structure may be constituted of a single layer or multi-layerstructure, and, in the case of the multi-layer structure, the type andcomponent ratio of compositions may differ for each layer.

The photosensitive silver salt contained in the photosensitivecomposition of the present invention refers to photosensitive silverhalides, or organic salts containing silver halides. The photosensitivesilver halides principally play a role of producing silver metal servingas a catalyst by exposure to light, and the organic salts principallyplay a role of converting the reducing agent into an oxidized product byreaction with the reducing agent.

The photosensitive silver halide may include silver chloride, silverbromide, silver chlorobromide, silver iodobromide and silverchloroiodobromide, and these may be subjected to chemical sensitizationor optical sensitization as conventionally done with respect to ordinaryphotographic emulsions. More specifically, usable as the chemicalsensitization are sulfur sensitization, noble metal sensitization andreduction sensitization, and utilizable as the optical sensitization aremethods in which conventionally well-known sensitizing dyes are used.

The organic silver salt includes silver salts of aliphatic carboxylicacids, of aromatic carboxylic acids, of thiocarbonyl compounds having amercapto group or α-hydrogen, and of imino group-containing compounds.

The aliphatic carboxylic acids include acetic acid, butyric acid,succinic acid, sebacic acid, adipic acid, oleic acid, linolic acid,linolenic acid, tartaric acid, palmitic acid, stearic acid, behenic acidand camphor acid, but, in general, silver salts having a smaller numberof carbon atoms are proportionally less stable, and hence those havingan appropriate number of carbon atoms are preferred. The aromaticcarboxylic acids include benzoic acid derivatives, quinolinic acidderivatives, naphthalene carboxylic acid derivatives, salicylic acidderivatives, gallic acid, tannic acid, phthalic acid, phenyl acetic acidderivatives, and pyromellitic acid.

The compounds having a mercapto or thiocarbonyl group include3-mercapto-4-phenyl-1,2,4-triazole, 2-mercaptobenzoimidazole,2-mercapto-5-aminothiadiazole, 2-mercaptobenzothiazole,s-alkylthioglycolic acid (alkyl group carbon atom number of 12 to 22),dithiocarboxylic acids such as dithioacetic acid, thiamides such asthiostearoamide, and mercapto compounds such as5-carboxy-1-methyl-2-phenyl-4-thiopyridine, mercaptotriazine,2-mercaptobenzoxazole, mercaptooxazole, and3-amino-5-benzylthio-1,2,4-triazole, which are described in U.S. Pat.No. 4,123,274.

The compounds having an imino group typically include benzotriazole orderivatives thereof, as described in Japanese Patent Publication Nos.44-30270 or 45-18416, as exemplified by benzotriazole andalkyl-substituted benzotriazoles such as methylbenzotriazole,halogen-substituted benzotriazoles such as 5-chlorobenzotriazole,carboimidobenzotriazoles such as butylcarboimidobenzotriazole,nitrobenzotriazoles, as described in Japanese Unexamined PatentPublication No. 58-118639, sulfobenzotriazole, carboxybenzotriazole orsalts thereof, or hydroxybenzotriazole, as described in JapaneseUnexamined Patent Publication No. 58-118639, 1,2,4-triazole, asdescribed in U.S. Pat. No. 4,220,709, or 1H-tetrazole, carbazole,saccharin, imidazole, and derivatives thereof. Of these, preferredorganic salts include organic salts of aliphatic carboxylic acids.

The reducing agent contained in the photosensitive composition of thepresent invention is changed into an oxidized product by action of thesilver metal as a catalyst, and include the compounds represented by thefollowing Formulas (I), (II) and (III) ##STR2##

In the above Formulas (I), (II) and (III), R¹, R², R³, R⁵ and R⁶ eachindependently represent a hydrogen atom, a halogen atom, a hydroxylgroup, a substituted or unsubstituted alkyl group, a substituted orunsubstituted aralkyl group, a substituted or unsubstituted aryl group,an alkoxyl group, or a substituted or unsubstituted cycloalkyl group; R⁴represents a hydrogen atom, a halogen atom, a substituted orunsubstituted alkyl group, a substituted or unsubstituted aralkyl group,a substituted or unsubstituted aryl group, a substituted orunsubstituted cycloalkyl group, a carboxyl group, or a carboxylic acidester group; A represents an oxygen atom, or a sulfur atom; R representsa hydrogen atom, an unsubstituted alkyl group, or a substituted orunsubstituted aralkyl group; n represents 0 or 1; and Z is a divalentlinking group and represents an alkylidene group, an aralkylidene group,or a sulfur atom.

Specific examples of the compound represented by Formula (I) include,for example, 1,4-dihydroxynaphthalene, 4-methoxy-1-naphthol,4-ethoxy-1-naphthol, 5-methyl-4-methoxy-1-naphthol,1,5-dihydroxynaphthalene, 4-chloro-1-naphthol, 5-chloro-1-naphthol,4-methylthio-1-naphthol, 4-ethylthio-1-naphthol,6-phenyl-4-methyl-1-naphthol, 6-phenyl-4-methoxy-1-naphthol,6-benzyl-1-naphthol, 6-benzyl-4-methoxy-1-naphthol,4-methyl-1,7-dihydroxynaphthalene, 4-methoxy-6-benzyl-1-naphthol,4-methoxy-6-cyclohexyl-1-naphthol, 4-methylthio-6-cyclohexyl-1-naphthol,3,4-dimethyl-1-naphthol, and 4-benzyloxy-1-naphthol.

Specific examples of the compound represented by Formula (II) include,for example, 8-hydroxyquinoline, 4,8-dihydroxyquinoline-2-carboxylicacid, 4-hydroxyquinoline-2-carboxylic acid, 4-methyl-8-hydroxyquinoline,4-benzyl-8-hydroxyquinoline, and 4,8-dihydroxy-5-methylquinoline.

Specific examples of the compound represented by Formula (III) include,for example, 2,2'-methylenebis(6-t-butyl-1,4-dihydroxybenzene),2,2'-methylenebis(4-methoxyphenol),2,2'-methylenebis(4,6-di-t-butylphenol),2,2'-methylenebis(4-methyl-6-t-butylphenol),2,2'-butylidenebis(4-methoxyphenol),2,2'-butylidenebis(6-t-butyl-1,4-dihydroxybenzene),2,2'-thiobis(4-methoxyphenol),2,2'-thiobis(6-methyl-1,4-dihydroxybenzene),2,2'-thiobis(4,6-di-t-butylphenol), bis(2-hydroxy-5-methylphenyl)phenylmethane, and(3-t-butyl-5-methyl-2-hydroxyphenyl)-(5-methoxy-2-hydroxyphenyl)methane.

Of the above reducing agents, two or more kinds may be used incombination, and it is also possible to use these compounds incombination with any conventionally known reducing agents so long as theobject of the present invention may not be hindered.

The photopolymerization initiator may include carbonyl compounds, sulfurcompounds, halogen compounds, and photopolymerization initiators ofredox type.

Specifically, the carbonyl compounds include diketones as exemplified bybenzyl, 4,4'-dimethoxybenzyl, diacetyl, and camphorquinone;benzophenones as exemplified by 4,4'bis(dimethylamino)benzophenone, and4,4'-dimethylbenzophenone; acetophenones as exemplified by acetophenone,4'-methoxyacetophenone; benzoin alkyl ethers; thioxanthones asexemplified by 2-chlorothioxanthone, 2,5-diethylthioxanthone, andthioxanthone-3-carboxylic acid-β-methoxy ethyl ester; chalcones andstyrylketones having a dialkylamino group; and cumarins as exemplifiedby 3,3'-carbonylbis(7-methoxycumarin), and3,3'-carbonylbis(7-diethylaminocumarin).

The sulfur compounds include disulfides as exemplified bydibenzothiazolyl sulfide, and decylphenyl sulfide.

The halogen compounds include, for example, carbon tetrabromide,quinolinesulfonyl chloride, and S-triazines having a trihalomethylgroup.

The photopolymerization initiators of redox type include those used incombination of a trivalent iron ionic compound (as exemplified by ferricammonium citrate) with a peroxide, and those used in combination of aphotoreducing dye such as riboflavin or Methylene Blue with a reducingagent such as triethanolamine or ascorbic acid.

In the photopolymerization initiator described above, two or morecompounds can also be used in combination to obtain a more efficientphotopolymerization reaction.

Such combination of the photopolymerization initiators includes acombination of chalcones and styrylketones having a dialkylamino groupor cumarins, with S-triazines having a trihalomethyl group orcamphorquinone.

Besides the above, diazo compounds or peroxides having aphotopolymerization initiating power can also be utilized as thephotopolymerization initiator. These polymerization initiators may alsobe used in combination of two or more kinds thereof, or in combinationwith the above compounds.

As the thermopolymerization initiator, known initiators can be used,which are in general roughly grouped into an azo initiator and aperoxide initiator.

First, the azo initiator refers to an organic compound having at leastone nitrogen-nitrogen double bond in its molecule, and may include, forexample, azobisisobutyronitrile, azobiscyclohexanecarbonitrile,azobismethylphenethylcarbonitrile, azobis-secamylonitrile,azobisphenylethane, azobiscyclohexylpropylonitrile,azobismethylchloroethane, tritylazobenzene, phenylazoisobutyronitrile,and 9-(p-nitrophenylazo)-9-phenylfluorenone.

The peroxide initiator includes almost all the compounds so long as theyare organic compounds having at least one oxygen-oxygen bond in themolecule. For example, it may include methyl ethyl ketone peroxide,cyclohexanone peroxide, 3,3,5-trimethylcyclohexanone peroxide,methylcyclohexanone peroxide, acetylacetone peroxide,1,1-bis(t-butylperoxy)-3,3,5-trimethylcyclohexane,1,1-bis(t-butylperoxy)cyclohexane,n-butyl-4,4-bis(t-butylperoxy)valerate, 2,2-bis(t-butylperoxy)butane,t-butyl hydroperoxide, cumene hydroperoxide, diisopropylbenzenehydroperoxide, p-menthane hydroperoxide,2,5-dimethylhexane-2-dihydroperoxide, 1,1,3,3-tetramethylbutylhydroperoxide, di-t-butyl peroxide, t-butylcumyl peroxide, dicumylperoxide, α,α'-bis(t-butylperoxyisopropyl)benzene,2,5-dimethyl-2,5-di(t-butylperoxy)hexane,2,5-dimethyl-2,5-di(t-butylperoxy) hexyne-3-acetyl peroxide, isobutyrlperoxide, octanoyl peroxide, decanoyl peroxide, lauroyl peroxide,3,5,5-trimethylhexanoyl peroxide, succinic acid peroxide, benzoylperoxide, 2,4-dichldorobenzoyl peroxide, m-toluoyl peroxide, diisopropylperoxydicarbonate, di-2-ethylhexyl peroxydicarbonate, di-n-propylperoxydicarbonate, di-2-ethoxyethyl peroxydicarbonate,dimethoxyisopropyl peroxydicarbonate,di(3-methyl-3-methoxybutyl)peroxydicarbonate, t-butyl peroxyacetate,t-butyl peroxyisobutyrate, t-butyl peroxypivarate, t-butylperoxyneodecanoate, t-butyl peroxyoctanoate, t-butylperoxy-3,5,5-trimethylhexanoate, t-butyl peroxylaurate, t-butylperoxybenzoate, di-t-diperoxyisophthalate,2,5-dimethyl-2,5-di(benzoylperoxy)hexane, t-butyl maleic acid peroxide,and t-peroxyisopropylcarbonate. Other known thermopolymerizationinitiators can also be used.

The photosensitive material of the present invention is illustrated inFIGS. 5A to 5D. The photosensitive material of the present invention canbe obtained by dissolving the above essential components in a solventtogether with additives (such as polymerization initiators) and bindersappropriately used, and coating the resulting solution on a support madeof metal, plastic or paper, followed by drying.

As illustrated in FIG. 5A, a support may not be required if thephotosensitive layer 1 itself can serve as a support, but, asillustrated in FIG. 5B, usually the photosensitive layer 1 is laminatedon the support 2. Further, as illustrated in FIG. 5C, an oxygeninhibitory layer 9 of PVA and the like may be provided on thephotosensitive layer 1 so that the photosensitive layer can be preventedfrom being affected by oxygen upon carrying out the polymerizationdescribed later, or, as illustrated in FIG. 5D, an image receivingmedium 8 as exemplified by art paper, coated paper, films and metal foilmay be provided on the photosensitive layer 1.

Alternatively, the above essential components may be formed intomicrocapsules together with the additives as used if desired (such asthe polymerization initiator) to form the photosensitive layer 1comprising the microcapsules 10 and a binder 11 (FIG. 5E).

The photosensitive material may be of any form including flat sheets,cylinders, rolls and so forth, without any particular limitations.

Suitable binders used in the present invention can be selected from awide range of resins.

They specifically include cellulose esters as exemplified bynitrocellulose, cellulose phosphate, cellulose sulfate, celluloseacetate, cellulose p cellulose palmitate, cellulose acetate.propionate,and cellulose acetate.butyrate; cellulose ethers as exemplified bymethyl cellulose, ethyl cellulose, propyl cellulose, and butylcellulose; vinyl resins as exemplified by polystyrene, polyvinylchloride, polyvinyl acetate, polyvinyl butyral, polyvinyl acetal,polyvinyl alcohol, and polyvinyl pyrrolidone; copolymer resins asexemplified by a styrene/butadiene copolymer, a styrene/acrylonitrilecopolymer, a styrene/butadiene/acrylonitrile copolymer, and a vinylchloride/vinyl acetate copolymer; acrylic resins as exemplified bypolymethyl methacrylate, polymethyl acrylate, polybutyl acrylate,polyacrylic acid, polymethacrylic acid, polyacrylamide, andpolyacrylonitrile; polyesters as exemplified by polyethyleneterephthalate; polyarylate resins as exemplified bypoly(4,4'-isopropylidene, diphenylene-co-1,4-cyclohexylenedimethylenecarbonate), poly(ethylenedioxy-3,3'-phenylene thiocarbonate),poly(4,4'-isopropylidene, diphenylene carbonate-co-terephthalate),poly(4,4'-isopropylidenediphenylene carbonate),poly(4,4'-sec-butylidenediphenylene carbonate), andpoly(4,4'-isopropylidenediphenylene carbonate-block-oxyethylene);polyamides; polyimides; epoxy resins; phenol resins; and polyolefins asexemplified by polyethylene, polypropylene, and chlorinatedpolyethylene.

Besides these, it is also possible to optionally add to thephotosensitive layer a coloring material, an antifoggant, aphoto-discoloration preventive agent, a solid solvent, a surface activeagent, an antistatic agent, etc.

In the photosensitive material, the components described above in detailmay preferably be used in the proportion as follows:

The silver halide may be contained in an amount of preferably for 0.001mol to 2 mols, and more preferably from 0.05 to 0.4 mol, per mol of theorganic silver salt. The reducing agent may be contained in an amount ofpreferably from 0.2 mol to 3 mols, and more preferably from 0.4 mol to1.3 mol, per mol of the organic silver salt. The polymerizationinitiator may be contained in an amount of preferably from 0.1 part byweight to 50 parts by weight, and more preferably from 0.5 part byweight to 30 parts by weight, based on 100 parts by weight of thepolymerizable polymer precursor. The polymerization initiator may becontained in an amount of preferably from 0.01 mol to 10 mols, and morepreferably from 1 mol to 3 mols, per mol of the reducing agent.

The photosensitive layer may have a film thickness of from 0.1 μm to 2mm, and preferably from 1 μm to 0.1 mm, in approximation.

Preferred mixing proportion of the above components in thephotosensitive layer may vary depending on the polymer image formingmethods to be employed, but employment of the polymerizable polymerprecursor having a melting point of 35° C. or more does not bring aboutany difference in the mixing ratio from the corresponding techniquesprovided prior to the present invention.

The image forming method of the present invention will be describedbelow.

The image forming method of the present invention includes a method (A),comprising the steps of imagewise exposure and heating, thereby forminga polymer image at an imagewise unexposed area, a method (B), comprisingcarrying out imagewise exposure and heating, followed by whole arealexposure to form a polymer image at the imagewise unexposed area, and amethod (C), comprising laminating the thus formed polymer image and animage receiving medium, and carrying out heating and pressing totransfer the imagewise unexposed area to the image receiving medium.

To exemplify the image forming method (A), it comprises the steps of;

(a) subjecting the photosensitive material to imagewise exposure to forma latent image, as in FIG. 1A;

(b) heating the photosensitive material on which the latent image hasbeen formed, to convert said latent image into a latent image comprisedof the above-described reducing agent and the oxidized product producedfrom said reducing agent by said heating, as in FIG. 1B; and

(c) allowing thermopolymerization to occur by utilizing thefirst-mentioned heating or by heating under new conditions to form apolymer image at the imagewise unexposed area produced in the step (a),as in FIG. 1C.

In this instance, the photosensitive material is required to contain thethermopolymerization initiator.

To exemplify the image forming method (B), it comprises the steps of;

(a) subjecting the photosensitive material to imagewise exposure to forma latent image, as in FIG. 2A;

(b) heating the photosensitive material (1) on which the latent imagehas been formed to convert said latent image into a latent imagecomprised of the above-described reducing agent and the oxidized productproduced from said reducing agent by said heating, as in FIG. 2B; and

(c) subjecting the photosensitive material having the latent imagecomprised of said reducing agent and oxidized product, to whole arealexposure to polymerize the above-described polymerizable polymerprecursor, corresponding to the distribution of said reducing agent andoxidized product, thereby forming a polymer image, as in FIG. 2C.

In this instance, the photosensitive material is required to contain thephotopolymerization initiator.

How each step in the method (A) or (B) proceeds will be furtherdescribed below with reference to FIGS. 1A, 1B, 1C, and FIGS. 2A, 2B and2C.

Step (a) in the image forming method (A) or (B) of the present invention(FIGS. 1A and 2A) is the step of carrying out the writing of an image bylight, where a photosensitive layer 1 on a support 2 is exposed to lightfor a desired image according to analog exposure using a mask or thelike, or digital exposure using a laser or the like to apply imagesignals such as external electric signals or photosignals, therebyexposing a desired image to light.

As a result, silver metals 3 are formed on the photosensitive silverhalide in an exposed area 1-a, which form the latent image. The silvermetals 3 thus formed act as a catalyst for the thermal reaction betweenthe organic silver salt and reducing agent contained in thephotosensitive layer 1.

The exposure at the stage of the writing of the latent image may becarried out by appropriately selecting conditions under which anydesired performances such as a sufficient contrast can be obtained inthe resulting polymer image, depending on the concentration, type, etc.of the silver halide contained in the photosensitive layer.

Since in this step the photosensitive silver halide is used, it becomespossible to effect the writing with a high sensitivity.

Next, in step (b) in the method (A) or (B) of the present invention(FIGS. 1B and 2B), the photosensitive material 1 on which the latentimage has been formed is heated, so that the silver metals 3 selectivelyact as a catalyst in the exposed area 1-a to cause the reaction betweenthe organic silver salt and reducing agent, where the organic silversalt is reduced to a silver atom and at the same time the reducing agentis oxidized to form an oxidized product 5.

As a result, there are formed the exposed area 1-a containing theoxidized product 5 and an unexposed area 1-b containing the reducingagent 4. Since, the reducing agent 4 used in the photosensitive material1 is oxidized to become an oxidized product having a polymerizationinhibitory power against the polymerizable polymer precursor, a latentimage which is ascribable to a difference in the polymerizationinhibitory power, constituted by the distribution of the oxidizedproducts 5, is formed on the photosensitive layer 1.

In the method (A), the thermopolymerization takes place at the same timewhen or after the latent image has been formed, thus forming apolymerized area 6 at the imagewise unexposed area, as in FIG. 1C.

The heating in this step (b) is carried out by appropriately selectingconditions necessary for the oxidation-reduction reaction to proceed.Though not broadly suitable since the heating depends on thecomposition, etc. of the photosensitive layer, the heating maypreferably be carried out at 60° C. to 180° C., and more preferably 100°C. to 150° C., for 1 second to 5 minutes, and more preferably 3 secondsto 60 seconds. In general, the heating at high temperatures is completedin a short time, and the heating at low temperatures taxes a long timeto complete heating. A heating means includes a method in which a hotplate, heat roll, thermal head or the like is used, as well as a methodin which a heating element of the support is electrified to carry outthe heating, or a method in which the heating is carried out byirradiation with laser beams. Usually the heating is made undersubstantially uniform heating.

Subsequently, step (c) in the method (B) of the present inventionfollows, but, before starting step (c), a transferring medium or thelike may be laminated on the surface to be exposed to light, for thepurpose of preventing the polymerization reaction from being inhibitedby oxygen.

In step (c) (FIG. 2C), the photosensitive layer 1 is subjected to wholeareal exposure to allow the photopolymerization initiator contained inthe layer to be decomposed, generating radical species. The radicalspecies cause the polymerization reaction to form a polymerized area 6in the photosensitive layer 1. Namely, since the concentration of theoxidized product having the polymerization inhibitory power differsbetween the exposed area 1-a and unexposed area 1-b, a difference in apolymerization state is produced between the exposed area 1-a andunexposed area 1-b, and this difference results in the formation of thepolymer image.

In the image forming methods (A) and (B) of the present invention, theoxidized product 5 has the polymerization inhibitory power and theunexposed area becomes the polymerized area, so that the polymer image,which is positive, can be formed.

As light sources used in the above steps (a) and (c), usable are, forexample, sunlight, tungsten lamps, mercury lamps, halogen lamps, xenonlamps, fluorescent lamps, LEDs, and lasers, and the wavelength of thelight used in these steps may be the same or different. Even if thelight having the same wavelength is used, the latent image can besufficiently written with use of light having an intensity of the levelthat may not cause photopolymerization in the above step (a), since thesilver halide usually has a sufficiently higher photosensitivity thanthe photopolymerization initiator.

In the above step (c), the photosensitive material may be additionallyheated for the purpose of accelerating photopolymerization, or remainingheat in the above step (b) may be utilized.

In the method (C), the polymer image thus obtained in the method (A) or(B) is laminated on the image receiving medium, followed by heating andpressing to transfer the unpolymerized area to the image receivingmedium.

The method (C) will be described with reference to FIGS. 3 and 4. FIG. 3illustrates a state in which the polymer image has been laminated, wherethe unpolymerized area 1 is transferred to the image receiving medium byheating and pressing, thus forming an image 8, as in FIG. 4, on theimage receiving medium. When this transfer is effected, the presentinvention, which employs the polymerizable polymer precursor having amelting point of 35° C. or more, can achieve an image which is free ofimage unclearness, has a good correspondence between the unpolymerizedarea 1 and the image area 8, and has a high resolution. The heating andpressing are required to be carried out under conditions such that thepolymerizable polymer precursor may give tackiness. Thus the heating maypreferably be carried out at a temperature of from 60° C. to 180° C.,and the pressing, preferably at a pressure of from 20 to 300 kg/m².

EXAMPLES

The present invention will be described below by giving Examples, butthe present invention is by no means limited to these. In the following,"part(s)" is/are by weight.

EXAMPLE 1 Preparation of microcapsules

In a mixed solvent of 45 parts of chloroform with 40 parts of methylethyl ketone, 30 parts of a polymerizable polymer precursor (m.p.75°-77° C.) having the structure shown below, 3.1 parts of a leuco dye,TG-11 (trade name, available from Nippon Kayaku Co., Ltd.) weredissolved. Subsequently, 0.8 part of behenic acid was added, followed byaddition of 1.0 part of silver behenate, and these were dispersed with ahomogenizer (5,000 rpm) for about 10 minutes. ##STR3##

Subsequently 0.2 part of AgBrm 0.35 part of 4-methoxynaphthol, 0.1 partof phthalazinone, 1.3 parts of 2-chlorothioxanthone and 0.6 part ofethyl p-dimethylaminobenzoate were added, and the mixture was furtherstirred for 30 minutes.

The dispersion thus prepared was encapsulated by the followingprocedures: 2.0% by weight of Isoban (trade name, available from KurarayCo., Ltd.) which is an isobutyrene-maleic anhydride copolymer, and 0.3%by weight of pectin were dissolved, which were added in 150 parts of anaqueous solution adjusted to pH 4.5 with sulfuric acid, and the mixturewas emulsified using a homogenizer at 7,000 rpm. While passing airtherethrough, the emulsion was stirred for about 3 hours, followed byaddition of 2 parts of melamine, 5.5 parts of an aqueous 50 wt % ureasolution and 12 parts of an aqueous 37% formalin solution to carry outreaction at 65° C. for 3 hours. Thereafter, the pH was adjusted to 9.0using 20% NaOH water, and 0.6 part of sodium bisulfate and 1.1 parts ofsodium sulfite were added, and the reaction mixture was left to cool.The resulting capsules had an average particle size of 8.6 μm.

Preparation of photosensitive sheet having image forming layer

To the above capsule dispersion, 40 parts of an aqueous 5.0% by weightpolyvinyl alcohol solution was added, and the solution was uniformlycoated on art paper of 45 g/m² so as to give a coating weight of 6 g/m².

Preparation of image receiving medium

In 125 g of water, 11 g of an aqueous 40% sodium hexametaphosphatesolution, and 30 g of a zinc salt of salicylic acid derivative (R-054;trade name, available from Sanko Kagaku K. K.), 60 g of 55% calciumcarbonate slurry and 20 g of active clay were further mixed, and themixture was milled with a ball mill. To 100 g of the solution obtained,3 g of 50% SBR latex and 20 g of 3% polyvinyl alcohol were added. Theresulting solution was uniformly coated on art paper of 45 g/m² so as togive a coating weight of 10 g/m². Thereafter, calendering was applied toobtain an image receiving medium.

Image formation

A mask comprising a line image of 20 μm, 30 μm and 40 μm in distance andwidth was brought into close contact with the above photosensitivesheet, and light from a fluorescent lamp of 360 nm with an electricpower of 20 W was irradiated thereon for 1 second. This was passedthrough a heat developing machine regulated to a temperature of 120° C.,and the light was further irradiated on the whole area for 30 seconds.This and the image receiving medium were put together, and allowed topass through a 80° C. heat roll applied with a pressure of 85 kg/cm². Asa result, a black line image corresponding to the imagewise exposed areawas produced on the image receiving medium side.

Example 2

Example 1 was repeated to form an image, except that the polymerizablepolymer precursor was replaced with 20 parts of a structure shown below,having a melting point of 51° to 55° C., and 5 parts ofdipentaerythritol hexaacrylate. ##STR4##

Comparative Example 1

Example 1 was repeated to obtain a photosensitive sheet, except that thepolymerizable polymer precursor was replaced with liquidtrimethylolpropane triacrylate. After the imagewise exposure, heatdevelopment and photopolymerization, the sheet and the image receivingmedium were put together, and allowed to pass through a roller appliedwith a pressure of 250 kg/cm² to obtain an image.

Example 3

Example 1 was repeated except that the polymerizable polymer precursorwas replaced with 20 parts of 1,6-bis[2-(acryloxy)acetoxy]hexane (m.p.63°-65° C.) and 5 parts of trimethylolpropane triacrylate. The abovepolymerizable polymer precursor mixture in a waxy state was melted at40° C. to turn into a transparent state.

Example 4

Example 1 was repeated except that the polymerizable polymer precursorwas replaced with 15 parts ofbis{[2-(acryloxy)ethoxycarbamoyl]cyclohexyl}methane (m.p. 125°-129° C.)and 5 parts of trimethylolpropane triacrylate. The above polymerizablepolymer precursor mixture in a waxy state was melted at 36° C. to turninto a transparent liquid state.

Comparative Example 2

Example 1 was repeated except that the polymerizable polymer precursorwas replaced with 1.2 parts of 1,6-bis[2-(acryloxy)acetoxy]hexane and 30parts of trimethylolpropane triacrylate. The above polymerizable polymerprecursor mixture was liquid at room temperature (25° C.).

Evaluation

As compared with Examples 1, 2, 3 and 4, Comparative Examples 1 and 2produced a strong unpleasant odor when the transfer processing wascarried out, and caused practical problems.

Resolution of the image obtained in each Examples 1 to 4 and ComparativeExamples 1 and 2 was measured by use of a microscope. Results obtainedare shown in Table 1.

                  TABLE 1                                                         ______________________________________                                                     Resolvable minimum line width                                    ______________________________________                                        Example 1       20 μm                                                      Example 2       25 μm                                                      Example 3       25 μm                                                      Example 4       25 μm                                                      Comparative Example 1                                                                         40 μm                                                      Comparative Example 2                                                                         40 μm                                                      ______________________________________                                    

Comparative Example 3

Example 1 was repeated to obtain a photosensitive sheet, except that thepolymerizable polymer precursor was replaced with NK-Ester 23G (tradename, available from Shin-Nakamura Chemical Co., Ltd.; m.p. 30° C.).After the imagewise exposure, heat development and photopolymerization,the sheet and the image receiving medium were put together, and allowedto pass through a roller applied with a pressure of 250 kg/cm² to obtainan image.

On this occasion, the image density was as low as 0.9 although it was1.4 in Comparative Example 1. Carrying out the transfer by heating andpressing under the same conditions as in Example 1 resulted in increaseof the image density to 1.4, but the resolvable minimum line width wasenlarged from 20 μm to 40 μm.

Example 5

In 10 parts of isopropanol, 0.8 part of polyvinyl butyral was dissolved,and 0.1 part of AgBr and 0.6 part of silver behenate were furtherdispersed in this solution. Subsequently, in the resulting dispersion,0.29 part of 4-methoxy-1-naphthol was dissolved to obtain Solution A.

Separately from the above, 0.15 part of 2-chlorothioxanthone, 0.18 partof ethyl p-dimethylaminobenzoate, 0.6 part of polymethyl methacrylateand 2.5 parts of 1,6-bis[2-(acryloxy)acetoxy]hexane (m.p. 63°-65° C.)were dissolved in 15 parts of methyl ethyl ketone to obtain Solution

Next, Solution B was thoroughly mixed with Solution A, and the resultingmixed solution was coated on a polyethylene terephthalate (PET) of 12 μmthick so as to give a dried film thickness of 2 μm to provide aphotosensitive layer, and a polyvinyl alcohol (PVA) layer of 2 μm thickwas further provided thereon, thus obtaining a photosensitive material.

Next, a mask film was superposed on the photosensitive material, whichwas imagewise exposed to light to form a latent image. This imagewiseexposure was carried out for 10 msec. on the photosensitive materialwith a distance of 5 cm from a light source, using as the light source afluorescent lamp having a fluorescent peak at 420 nm and a luminousoutput of 5 mW.

Thereafter the mask was removed, and the photosensitive material wasallowed to pass in 20 seconds through a heat developing machineregulated to 105° C. Further, the photosensitive material was put on ahot plate heated to 60° C., and light from a fluorescent lamp having afluorescent peak at 390 nm and a luminous output of 10 mW was irradiatedthereon for 10 seconds with a distance of 5 cm.

As a final step, the PVA layer was removed by washing with water, andthereafter the photosensitive material was rinsed in ethanol. As aresult, the imagewise exposed area was removed from the PET film, and asharp positive image comprised of the polymerized area remained on thePET film.

The processing in the present Example was carried out entirely undersafety light.

Comparative Example 4

Example 5 was repeated to obtain a photosensitive material, except that2.5 parts of 1,6-bis[2-(acryloxy)acetoxy]hexane in Example 5 wasreplaced with 2.5 parts of trimethylolpropane triacrylate.

After this photosensitive material was imagewise exposed to light, itwas allowed to pass through a heat developing machine regulated to 105°C., followed by whole areal exposure to form a polymer image, to find,however, that the image had no sharpness after etching processing.

The photosensitive materials prepared in Example 5 and ComparativeExample 4 were subjected to storage resistance tests for 2,000 hoursunder safety light and under conditions of 35° C. and 70% RH, show thatfogging was produced on the photosensitive material of ComparativeExample 4, but no fogging was produced on the photosensitive material ofExample 5.

Example 6

    ______________________________________                                        AgBr                     0.1    part                                          Silver behenate          0.7    part                                          Isopropyl alcohol/toluene (1/1)                                                                        15.0   parts                                         4-Benzyloxy-1-naphthol   0.4    part                                          Polymethyl methacrylate  3.0    parts                                         1,12-Bis[2-(acryloxy)acetoxy]dodecane                                                                  1.5    parts                                         (m.p. 70-72° C.)                                                       7-Methoxy-3-benzoylcumarin                                                                             0.16   part                                          Ethyl-4-dimethylaminobenzoate                                                                          0.04   part                                          ______________________________________                                    

A solution with the above formulation was thoroughly mixed by dispersionwith a dispersion mixer to prepare an emulsion. Next, the emulsion wascoated on a polyester film of 50 μm thick using a bar coater, followedby drying to form a photosensitive layer of 5 μm thick, and thereafter apolyester film of 12 μm thick was laminated thereon. Subsequently, thephotosensitive layer was imagewise exposed to light of about 400 nm ormore for 5 seconds through a cut filter (Y-42, tradename, available fromToshiba Glass Co., Ltd.), using an ultrahigh-pressure mercury lamp(VSH-500D, tradename, manufactured by Ushio Inc.) as a light source.Next, the photosensitive layer was heated at 115° C. for 10 seconds toeffect thermal amplification of the silver halide latent image.Subsequently the above filter was removed, followed by exposure to lightfor 20 seconds. Thereafter, the polyester film was peeled off. Then aplain paper and the photosensitive layer were superposed, heated to 80°C., and allowed to pass between rollers applied with a pressure of 25kg/cm², followed by peeling. The photosensitive layer corresponding tothe unexposed area was transferred on the plain paper, and littleremainded on the polyester film.

Comparative Example 5

Example 6 was repeated to form a photosensitive material and to makeevaluation, except that 1,12-bis[2-(acryloxy)acetoxy]dodecane in Example6 was replaced with a liquid polymerizable polymer precursor. Thephotosensitive layer corresponding to the unexposed area was transferredon the plain paper, but partially remained on the polyester film, andyet with an inconstant remaining rate.

Example 7

    ______________________________________                                        AgBr                       0.1    part                                        Silver behenate            0.7    part                                        Isopropyl alcohol/toluene (1/1)                                                                          10.0   parts                                       Methyl methacrylate/butyl acrylate copolymer                                                             2.0    parts                                       4,8-Dihydroxyquinoline-2-carboxylic acid                                                                 0.35   part                                        1,3-Bis[2-(acryloxyacetoxy)ethoxycarbamoyl]benzene                                                       1.8    parts                                       Dipentaerythritol heaxaacrylate                                                                          0.2    part                                        7-Methoxy-3-benzoylcumarin 0.16   part                                        Ethyl-4-dimethylaminobenzoate                                                                            0.04   part                                        ______________________________________                                    

A solution with the above formulation was thoroughly mixed by dispersionwith a dispersion mixer to prepare an emulsion. Next, the emulsion wascoated on a polyester film of 50 μm thick using an applicator, followedby drying to form a photosensitive layer of 5 μm thick. Thereafter apolyester film of 12 μm thick was laminated thereon. Subsequently, thephotosensitive layer was imagewise exposed to light for 5 seconds, usinga tungsten daylight lamp as a light source. Next, the photosensitivelayer was heated at 120° C. for 20 seconds to effect thermalamplification of the silver halide latent image. Subsequently, using anultraviolet fluorescent lamp, the whole areal exposure was carried outfor 60 seconds. Thereafter, the polyester film on the photosensitivelayer was peeled therefrom, and developing was carried out with carbonblack by using a fur brush. As a result, the carbon black adhered on theexposed area (unpolymerized area) and no carbon adhered on the unexposedarea (polymerized area), resulting in the formation of a black patternwith an excellent resolution.

As for the resolution of the black pattern, a pattern with a line widthof 10 μm was resolvable, also with a good image sharpness.

Comparative Example 6

Example 7 was repeated except that1,3-bis[2-(acryloxyacetoxy)ethoxycarbamoyl]benzene was replaced withtrimethylolpropane trimethacrylate.

The resulting image with a black pattern was not constant in the linewidth of 10 μm. The photosensitive materials prepared in Example 7 andComparative Example 6 were also subjected to storage resistance testsfor 2,000 hours under safety light and under conditions of 35° C. and70% RH, show that fogging was produced on the photosensitive material ofComparative Example 6, but only slight fogging hardly produced on thephotosensitive material of Example 7.

Example 8

    ______________________________________                                        AgBr                     0.1    part                                          Silver behenate          0.7    part                                          Isopropyl alcohol/toluene (1/1)                                                                        10.0   parts                                         Polyvinyl butyral        2.0    parts                                         2,2'-Methylenebis(4-methoxyphenol)                                                                     0.4    part                                          1,4-Bis[2-(acryloxyacetoxy)ethoxy-                                                                     2.5    parts                                         carbamoyl]cyclohexane (m.p. 104-106° C.)                               Azobisisobutyronitrile   0.5    part                                          Phthalazinone            0.1    part                                          ______________________________________                                    

A solution with the above formulation was thoroughly mixed by dispersionwith a dispersion mixer to prepare an emulsion. Next, the emulsion wascoated on a polyester film of 50 μm thick using an applicator, followedby drying to form a photosensitive layer of 5 μm thick. Thereafter apolyester film of 12 μm thick was laminated thereon. Subsequently, thephotosensitive layer was imagewise exposed to light for 10 seconds,using a tungsten daylight lamp as a light source. Next, thephotosensitive layer was heated for 40 seconds using a heat developingmachine regulated to 80° C., and then heated for 10 seconds using a heatdeveloping machine regulated to 110° C. Thereafter the polyester film of12 μm thick was peeled and kept immersed in an ethanol bath, so that theimagewise exposed area was dissolved and a polymer image remained on thefilm.

As described above in detail, the use of the photosensitive compositionin which the polymerizable polymer precursor having a melting point of35° C. or more is used enabled formation of an image without generationof unpleasant odor, complicated processing, and lack of image sharpness,according to various embodiments.

We claim:
 1. A photosensitive material, comprising: (a) a photosensitivesilver halide, (b) an organic silver salt, (c) at least one reducingagent selected from the compound represented by Formula (I), (II) or(III) shown below: ##STR5## materials (a), (b) and (c) being adapted toprovide an imagewise oxidized product of said reducing agent whensubjected to an imagewise exposure and heat development, (d) apolymerizable polymer precursor substantially insoluble in water andhaving a melting point of from 35° C. to 140° C., said polymerizablepolymer precursor being inhibited against polymerization in the presenceof said oxidized product, and (e) a polymerization initiator containedin an amount of from 0.01 mol to 10 mol per mol of said compound, saidpolymerization initiator being a photopolymerization initiator; whereinR¹, R², R³, R⁵ and R⁶ each independently are a hydrogen atom, a halogenatom, a hydroxyl group, an alkyl group, a substituted or unsubstitutedaralkyl group, a substituted or unsubstituted aryl group, an alkoxygroup, or a substituted or unsubstituted cycloalkyl group; R⁴ are ahydrogen atom, a halogen atom, an alkyl group, a substituted orunsubstituted aralkyl group, a substituted or unsubstituted aryl group,a substituted or unsubstituted cycloalkyl group, a carboxyl group, or acarboxylic acid ester group; A are an oxygen atom or a sulfur atom; Rare a hydrogen atom, an alkyl group or a substituted or unsubstitutedaralkyl group; n represents 0 or 1; and Z is a divalent linking groupand are an alkylidene group, an aralkylidene group or a sulfur atom andwhen said photosensitive material is imagewise exposed to light with awavelength of 400 to 900 nm, heated to 60° to 180° C. and exposed tolight with a wavelength of 250 to 700 nm, an area of said photosensitivematerial corresponding to an unexposed area of said photosensitivematerial is polymerized.
 2. The photosensitive material according toclaim 1, wherein said photosensitive silver halide is contained in anamount of from 0.001 mol to 2 mols per mol of said organic silver salt.3. The photosensitive material according to claim 1, wherein at leastone compound selected from said compound represented by Formula (I),(II) or (III) is contained in an amount of from 0.2 mol to 3 mols permol of said organic silver salt.
 4. The photosensitive materialaccording to claim 1, wherein said photopolymerization initiator iscontained in an amount of from 0.1 part by weight to 50 parts by weightbased on 100 parts by weight of said polymerizable polymer precursorhaving a melting point of 35° C. or more.
 5. The photosensitive materialaccording to claim 1, wherein said photosensitive material has athickness of from 0.1 μm to 2 mm.
 6. The photosensitive materialaccording to claim 1, wherein said photosensitive material furthercomprises a support.